In my post on LPWAN (low power wide area networks) I explained there are two categories of technologies and protocols in this segment of wireless Internet of Things (IoT) communication solutions.
The first category consists of LPWA network technologies using the unlicensed spectrum such as LoRaWAN, Sigfox and Ingenu. The second category uses the licensed spectrum of cellular networks and consists of eMTC, NB-IoT and EC-GSM-IoT. In this blog post we look at NB-IoT. However, let’s start with an introduction to these three cellular LPWA network standards.
The cellular LPWA standards in a nutshell
As I write in my IoT book Digitize or Die, eMTC, NB-IoT and EC-GSM-IoT are evolutions of existing mobile/cellular technologies for existing cellular network operators.
They enable them to leverage their existing geographic base stations’ footprint, private radio spectrum (which ensures no coexistence issue with other cellular networks) and market access.
EC-GSM-IoT (Extended Coverage GSM for IoT) is an improvement of GSM technologies because GSM is still a dominant mobile technology in numerous markets. It also enables operators to extend the usage of their important 2G legacy installed base. eMTC (enhanced Machine Type Communication, nowadays mainly referred to as LTE-M) and NB-IoT (Narrow Band Internet of Things) can be deployed together with legacy Long Term Evolution networks, or as stand-alone, in a reframed GSM carrier. They require a software upgrade of existing network infrastructure.
The standardization of the three cellular LPWA network technologies was completed in the Summer of 2016 by 3GPP (the 3rd Generation Partnership Project). The image below from Devopedia gives an overview of the three.
What you should know about NB-IoT
NB-IoT and LTE-M (eMTC) are far from omnipresent at the time of writing this post. It’s important to note that while LTE-M and NB-IoT networks are being rolled out there can be compatibility issues and operator-specific differences, certainly with NB-IoT.
This is because NB-IoT, which was a late response from the GSMA (and 3GPP) to come up with a solution to counter non-cellular LPWAN players who had filled a gap the 3GPP didn’t address in due time for evolving IoT needs, came with two approaches. On one hand there were Nokia and Ericsson who came with a solution that was able to work with 4G devices (and really is a cut down and lower power variant of 4G as Nick Hunn explains) while Huawei and Vodafone came with an alternative approach. In all the NB-IoT rush, both different ad even incompatible approaches, were withheld in the 3GPP standard.
In general, you can see NB-IoT (so, short for Narrowband IoT and known as LTE Cat-NB1 or LTE Cat-M2) the cellular IoT standard that is the main answer of the mobile industry to Sigfox and LoRaWAN. This also means that from a use case perspective you will find most overlaps between cellular and non-cellular LPWA here. However, on top of technological differences there are also different applications which are envisaged.
Below are some facts to know about NB-IoT:
- NB-IoT can coexist with LTE and with 2G, 3G and 4G in stand-alone operation. NB-IoT was designed to be rolled out as a software upgrade to mobile carrier networks (as was the case with LTE-M) but interoperability issues have made this a challenge, further complicated by different approaches.
- Narrowband IoT is generally accepted as being the better option for use cases and applications with static sensors. There are, for example, quite some initiatives in the scope of digital metering, one of the two main drivers of the LPWAN market overall.
- Geographically, at the time of writing this NB-IoT is being trialed and rolled out across the globe but especially China and Europe have been working with NB-IoT. Just as is the case in some European countries, in the US, in Japan and in Australia, there is a focus on offering both LTE-M and NB-IoT (although LTE-M is leading in the US). In some countries operators offer LTE-M and LoRaWAN while others have all options (on top of Sigfox): LoRaWAN, LTE-M and NB-IoT.
- While non-cellular LPWAN is not just for network operators, cellular LPWA network technologies by default are. This is also the case for NB-IoT. The ability to work with existing operators, even if many also offer LPWAN options in the unlicensed band as mentioned, is a benefit for many companies. The chart from IoT Analytics below shows where NB-IoT stands (end 2018) in the network operator landscape.
NB-IoT and operator choices: things to considers
NB-IoT uses a subset of the LTE standard (several principles and building blocks of the physical layer and higher protocol layers of LTE – more about such layers in my post on the OSI model).
It was designed to work within a single narrow band of 200KHz, which also explains the name Narrowband IoT. 200 Khz is the channel bandwidth used by 2G for voice transmission. GSM technology uses a carrier separation, dividing each 200kHz channel into eight 25kHz time-slots.
While some mobile carriers have already shut down their 2G networks other carriers don’t plan a 2G sunset soon with some saying it makes more sense to keep 2G networks for existing M2M applications and shut down 3G networks first. At the same time some carriers have already invested a lot in LTE networks, whereas others haven’t. These are just some of the other reasons why NB-IoT strategies of operators differ. Additional factors include existing partnerships, for instance with hardware vendors, where shifts are happening due to political and other challenges.
Nevertheless, NB-IoT will be rolled out pretty much everywhere since it lends itself to the various approaches of operators because it can work in different ways such as using re-farmed 2G spectrum or in LTE systems with in-band dedicated spectrum which, according to the GSMA, is how most early commercial NB-IoT networks were deployed.
The roll-out and expected growth of NB-IoT
The number of companies with NB-IoT chips, modules and gateways has increased a lot in the past year and the industry is pushing hard to make NB-IoT a success with aggressive pricing, partnerships enabling operators to roll out in the most cost-effective way and a lot of marketing. Moreover, the number of NB-IoT roll-outs has grown.
Researchers expect that by 2023, when a total of 1 Billion LPWAN (cellular and non-cellular) is expected, NB-IoT and LTE-M will have a market share of 55% of all LPWAN connections and these cellular LPWAN standards will overtake non-cellular technologies for the first time.
In my next post on a second 3GPP standard, LTE-M, I will compare both with more technical details. In a later post that concludes my series on LPWAN (cellular and non-cellular) you will find a handy comparison of all existing options.
To stay tuned on the roll-out of NB-IoT and considering various approaches there are several sources such as the GSMA and chip/module vendors. It’s important to keep in mind the mentioned geographical differences that also show in the expected growth of the cellular IoT module and cellular IoT gateway markets – and that not all NB-IoT roll-outs are the same. Below is a map, courtesy of Sierra Wireless.